External eye diseases such as blepharonconjunctivitis, meibomian gland dysfunction, (MGD), and chalazia are common causes of chronic ocular disease and irriatation. The ultimate objective of this study is to determine the role of meibomian gland lipids in such external eye diseases. At present, about 85% of the lipid classes that the meibomian glands produce have been identified. They are: hydrocarbons, sterol esters, wax esters, three types of diesters, triacyl glycerols, free fatty acids, and free cholesterol. We propose to identify the remaining 15%, then analyze all the lipids, first from normal humans and establish a range of variation, then from patients with such eye diseases, and see whether there are any significant differences from normal. We shall analyze by ultramicro techniques we have developed for sample sizes which we expect to obtain from individuals (i.e. 100 to 800 Mg). These include prep TLC (thin layer chromotography) followed by weighing the recovered lipid on a micro balance, analysis on the Iatroscan Th-10 (which is TLC with flame ionization detection), and analysis by gas liquid chromatography on chemically bonded phase to fused silica capillary columns. Both the latter two techniques are sensitive to the low nanogram level. We shall also examine the morphology of meibomian glands of all "normals" and patients by a technique of transillumination biomicroscopy and infrared photography and rate the dysfunction as mild, moderate, or severe according to the degree of distortion their meibomian glands show. We shall also collect lid margin samples for microbiological culture. Finally, by correlation of data from the lipid analyses, plus the objective evaluation of severity of MGD, plus the results of the microbiological cultures, we hope to gain insight into the etiology of these diseases. In addition to disease states mentioned above, meibomian gland lipids are also involved in tearfilm dynamics and contact lens wear problems, and these will be the subject of future investigations.